Table of Contents
Messaging WG
Overview
Evaluate middleware solutions for communication between GCS, drone, cloud, and between processes running on the vehicle. Select the best solution and evaluate ROS compatibility.
Some requirements include:
- Robust, SW messaging solution for commercial deployments of PX4
- Needs to scale to optimally support remote connections over an unreliable link, to onboard interprocess communication, and in-process communication.
- On-board heterogeneous compute (i.e. between different types of SoC core running parts of the flight stack) to be handled by a communication bridge.
- Extensible serialization format
Weekly Messaging WG Meetings: Google Hangout, Thurs mornings PT.
Current Status
The majority of the work to date has been done by eProsima on creating a bridge between uORB and RTPS. There are repositories on Github and videos on YouTube of the progress to date:
Intel is actively working on support FastRTPS on Aero:
Open Issues
There are a few open issues to resolve:
- Whether to support ROS via full ROS2 support and existing ROS2 to ROS bridge or create a MAVROS impelmentation that works with RTPS
- PX4 Integration plan
- The details of the PX4 integration plan need to be flushed out
- Snapdragon FastRPC support, OMG IDL and DDS RPC
- Investigate the best architecture for integration of FastRTPS with FastRPC
- Serialization format
- ROS2 uses ROS serialization format which is currently not extensible
- 3DR had selected Cap n' Proto for serialization
Previous Analysis
3DR analysis and discussion on Middleware:
3DR analysis of serialization protocols:
OSRF Analysis of RTPS and why it was selected for ROS2:
Links to other middleware comparisons:
The benefits of RTPS over alternatives is:
- Industry standard with several commercial and open source providers
- Can handle unreliable links
- Performance is good, and better performers have fewer needed features
- Potential compatibility with ROS2 (depends on serialization used)
